Análise da população de bactérias ácido-láticas (BAL) vaginais em resposta à progesterona e ao estrógeno em ovelhas pré púberes

Abstract

The microbiota comprehends the microrganisms that inhabit a given body compartment of a live organismo and may be related to the state of health of the host. The vaginal environment, including the local microbiota and the redox equilibrium, seems to be under the regulation of hormonal fluctuations, particularly that of ovarian steroids. This study aimed to investigate the effect of progesterone alone or progesterone followed by estradiol benzoate exogenous supplementation on the lactic acid population, reactive oxygen species production and antioxidant potential in the vaginal environment of prepubertal ewe lambs. Ten prepubertal ewe lambs were randomly divided to receive or not an intramuscular injection of a long- acting progesterone on day zero (D0), followed by an injection of estradiol benzoate (EB) on D5 to all ten females. The female group receiving both P4 and EB was called PE group, whereas the female group receiving only EB was called E group. On D0, D2 and D7 vaginal samples from all animals were collected by swab into a sterile saline solution, diluted 1:10, 10-3 e 10-5 and seeded on blood agar, in triplicates; alternatively, samples in saline were diluted 1:10 and 10-4 and seeded on MRS agar (De Man, Rogosa and Sharpe) by the pour plate method, in triplicates. Three months later, the experiment was repeated with the same animals aiming to collect vaginal washings. ON D0, D2 and D7 all the animals were sampled by infusing 5 ml of sterile saline in to the vagina fornix, followed by solution recovery into a sterile tube and storage at -20oC. Vaginal washings were assessed for ROS production and antioxidant potential. The data were analyzed by repeated measures analysis of variance, considering the effects of treatment (E and PE), day (D0, D2, D7) and their interaction. No effect of treatment was detected for the assessed variables. The effect of day, highly influenced by the EB treatment effect on D5, induced an increase on the CFU of vaginal BALs and antioxidant potential of vaginal cells, and a reduction of ROS production in vaginal cells and vaginal washings. An enrichment of lactobacillus colonies over time was also observed. In conclusion, estrogen favors the growth of vaginal lactic acid bacteria and the establishment of a more antioxidant vaginal environment, which seems to be related to the observed shift of the microbiota favoring the establishment of lactobacillus.